Nuclear Proliferation

nuclear weapons

nuclear weapons, weapons of mass destruction powered by atomic, rather than chemical, processes. Nuclear weapons produce large explosions and hazardous radioactive byproducts by means of either nuclear fission or nuclear fusion. Nuclear weapons can be delivered by artillery, plane, ship, or ballistic missile (ICBM); some can also fit inside a suitcase. Tactical nuclear weapons can have the explosive power of a fraction of a kiloton (one kiloton equals 1,000 tons of TNT), while strategic nuclear weapons can produce thousands of kilotons of explosive force. After World War II, the proliferation of nuclear weapons became an increasing cause of concern throughout the world. At the end of the 20th cent. the vast majority of such weapons were held by the United States and the USSR; smaller numbers were held by Great Britain, France, China, India, and Pakistan. Israel also has nuclear weapons but has not confirmed that fact publicly; North Korea has conducted nuclear test explosions but probably does not have a readily deliverable nuclear weapon; and South Africa formerly had a small arsenal. Over a dozen other countries can, or soon could, make nuclear weapons. In addition to the danger of radioactive fallout, in the 1970s scientists began investigating the potential impact of nuclear war on the environment. The collective effects of the environmental damage that could result from a large number of nuclear explosions has been termed nuclear winter. Treaties have been signed limiting certain aspects of nuclear testing and development. Although the absolute numbers of nuclear warheads and delivery vehicles have declined since the end of the cold war, disarmament remains a distant goal. See atomic bomb; cold war; disarmament, nuclear; guided missile; hydrogen bomb; nuclear energy; nuclear physics.